The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 71878fa46c7e3b40fa7b3f1b6e4ba3f92f1ac359 Mon Sep 17 00:00:00 2001
From: Greg Kurz groug@kaod.org Date: Sat, 3 Oct 2020 12:02:03 +0200 Subject: [PATCH] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()
The open-coded computation of the used size doesn't take the event into account when the VIRTIO_RING_F_EVENT_IDX feature is present. Fix that by using vhost_get_used_size().
Fixes: 8ea8cf89e19a ("vhost: support event index") Cc: stable@vger.kernel.org Signed-off-by: Greg Kurz groug@kaod.org Link: https://lore.kernel.org/r/160171932300.284610.11846106312938909461.stgit@bah... Signed-off-by: Michael S. Tsirkin mst@redhat.com
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c3b49975dc28..9d2c225fb518 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1519,8 +1519,7 @@ static long vhost_vring_set_addr(struct vhost_dev *d, /* Also validate log access for used ring if enabled. */ if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && !log_access_ok(vq->log_base, a.log_guest_addr, - sizeof *vq->used + - vq->num * sizeof *vq->used->ring)) + vhost_get_used_size(vq, vq->num))) return -EINVAL; }